Centrifugal pump



Patented July 17, 1931 warren SPTATES PATENT OFFICE Jomr mean, or As'rom- PENNSYLVANIA, ASSIGNOB To INGERSOLL-RAND coin PM, or JERSEY CITY, NEW JERSEY, A CORPORATION on NEW JERSEY GENTRIFUGAL PUMP v Application filed December 20, 1928. Serial my. 327,894.

This invention relates to centrifugal pumps and more particularly to improvement in hotwell pumps of the type disclosed in the patent to James K. McIntyre No. 1,680,057, filed September 23, 1926, bearing Serial No. 137,297.

The primary object of'this invention is to increase'the efiiciency of a multiple stage centrifugal pump in which the suction pressure is extremely low in the first stage. To-

wards this end the invention contemplates the interposition of a sliding valve between the two stages of the pump which valve is operable by the level of fluid in the hotwell pump to admit fluid to the second stage in proportion to the pressure developed in the first stage.

This ap licationcontains the subject matterkindred ber 20, 1928 by me for improvement in acentrifugal pump and the general objects of this invention have been fully set forth'in this co-pending application.

' A more specific object of the invention is the interposition of a valve near the first stage which is adapted to close off the outlet from the first stage impellerto causethe pump to operate more efliciently.

This invention contemplates in its broadest aspect-theprovision of a fluid level tank on the hotwell having therein a float which is operable to open or close a valvelocated in the steam line leading to a steam motor, which motor operates to adjust the valve closing the outlets from the'first stage impeller, sothat a predetermined head may be maintained at the. discharge of the first stage impeller untilizing the level of fluid in the hot-' well as a means of control. In this manner the work performed by the first stage and its thrust is kept constant regardless of the quantity of water removed;

hese objects have been accomplished by means of the structure shown in the accompanyingdrawings in which Figure 1 is a sectional view taken longitudinally through the pump.

Figure 2 is a sectional view of a specific pump, means whereby the level of water in to that of my co-p'endingapplica- 20 t1on bearingSerial No. 327,392, filed Decemthe hotwell determines the pressure to be developed ,in the first stage.

A pump is shown as being mounted on a suitable support 10 upon which there is a casing formed of an upper part 11 and a lower part 12. The lower part 12 is provided with a base 13. A drive shaft 14 extending between the upper and lower parts 11 and'12 lies in a horizontal plane and is suitably mounted on bearings 6 so as to permit the same to rotate within the-casing. Referring now to Figure 1, it will be seen that the pump is of the two stage type, there pump asshown is designed to bringt e pressure up to at least atmospheric pressure. The second stage wheel or impeller 18 is provided with 'a comparatively small inlet 22 and a small discharge opening 24.. This second impeller is designed to work with a slight pressure at the inlet.

The casing 13 of the pump is provided with an 1 inlet 26 leading to the first stage wheel and this inlet is located between the two impellers 16 and 18. The passage 30 leading to the impeller inlets 19 is formed by webs 32 cast integrally with the upper and lower parts 11 and 12 respectively of the casing.

These webs also serve as a partition to form part of the discharge passage 34 leading from the first stage impeller outlets to the second stage impeller inlets. The second stage impeller 18 is surrounded by a passage 36 leading to a discharge opening 38 .for connection with a suitable delivery pipe.

The above mentioned parts are incidental to the true invention asthey are simply the well-known elements that cooperate to make up a centrifugal pump of the type patented to McIntyre as cited above and no claim as to their novelty is made. The invention resides rather in the arrangement of parts to be more fully describedand claimed.

A bushing 39 is disposed on the shaft 14 and aworm gear 42, cup shaped in crosssection, is mounted on this bushing. This worm gear has threads 44 on its periphery of ,a relatively smallpitch.

A valve member 46 is mounted on the worm gear 42 and this valve is provided with internal teeth 48, meshing with the teeth 44 on the worm gear 42. The valve member 46 is provided with a flange 50, which flange is slidable over the outlet openings 20 of the first stage impeller and thusit will be seen that the valve member 46 has a limited movement on the Worm gear 42 so as to permit the same to partially close or completely close the outlet openings, of the first stage impeller to maintain a constant head on the same.

The valve member 46 is controlled indirectly by the level of the fluid in the hot well and is operated by means of a steam driven motor controlled by means responsive to fluid level .fluctuations in the hot well.

Toward this end a shaft 60 is shown as being mounted in suitable bearing supports in the upper casin 11. The shaft 60 has .a gear 62 thereon, a apted to mesh with teeth 64 on the periphery of-the valve member 46. A steam motor M is supported by a bracket 68 which is preferably secured to the pump casing. -This motor comprises a casing 70 in'which is mounted for rotation a pair of meshing gears 72. The casing has port 74 and port 76 between which these gears are mounted. The motor M is reversible and when rotated inone direction the port 74 is for the inlet of steam and port 76 is for ex- ,haust. In the reverse direction of motor rotation the port 76 is for steam inlet and port 74 for exhaust. The main steam line is shown at 78 and is connected to a valve chamber 80. This valve chamber 80 is provided with inlet ports 82, and outlet ports 84 and 86.

.A reversing D slide valve 88 is mounted within the casing 80 and this valve has bear-v ing surfaces 90-and 91 adapted to close the ports 84 and 86 leading from'the chamber. An exhaust line 98 leads from a port 96- in-. termediate ports 84 and 86 to the condenser inlet or any suitable point on the intake side of the condenser (not shown) so as to recover ondensate from the steam utilized in operating the pump; The valve 88 is controlled by the liquid in thehotwell 94 by means of a .pellers,

port 76, the-valve 88 and through the'exhaust 98, thereby rotating the pump in one direction andcausing the valve 46 to slide longitudinally of the impeller 16 to partially close the outlets 20. By'restricting the outlets 20 the discharge of the first stage impeller will be reduced so that that impeller will at all times operate against a full discharge head and will therefor not cavitate. Under these conditions, dueto the constant speed of the pum shaft 14, the pressure against which the rst stage pump works is constant and the thrust on the impeller remains constant.

When the outlets 20 are sufiiciently restricted so that the level of fluid in the hotwell rises the valve 88 is raised to close the ort 84 and to uncover the port 86. Steam w' 1 then pass through the ports 86 and 76 to rotate the motor in a reverse direction for-withdrawing the valve 46 to uncover the outlets 20 in. the first stage impeller. The latter position of the valve 88 is that which it assumes when the condenser is operating under conditions when the supply of condensate to the pump is substantially normal. Thus it will be seen that the valve 46, automatic in its operation, serves at all times to maintain a constant head and thrust on the first stage wheel.

I claim:

1. A multiple stage stage impeller, a common shaft for said impellers, each impeller being adapted to receive fluid from a fluid inlet and to discharge the same with increased head throu h a flu1d outlet, a rotatable valve adapted to e moved longitudinally with respect to the shaft across the opening at the outlet of the first stage impeller, a motor to actuate the valve, and means res onsive to the fluctuation in quailtity of fluld supplied to the pumpmg system for controlling said motor.

2, A multiple stage pumping system mcluding a first stage impeller and a second stage impeller, a common shaft for said imeach impeller being adapted to receive fluid from a fluid inlet and to discharge the same with increased head through a fluid' puinping system including a first stage impeller and a second.

outlet, a threaded member concentric with Y the shaft and, adjacent the said first stage impeller, a circular valve threaded to engage said threadedmeinber and arranged to in close the outlet of said first stage impeller and a motor controlled fluctuation in quantity of fluid supply to t e pumping system for rotating said valve: on said threaded member,

. whereby said valve member is adapted to close or open the outlet of said firstimpeller.

.back and forth across the opening at the outlet of the first stage impeller, means to actuate the valve, and means responsive to the fluctuation in quantity of fluid supplied to the pumping system for controlling said actuat- 1n means and thereby the movements of the va ve.

In testimony whereof Ihave signed this specification.

JOHN KIRGAN. 

